1. Field of the Invention
The present invention relates to communications networks, and more specifically, to user assignment strategies within hierarchical voice-and-data overlay networks.
2. Description of the Related Art
Some of the major challenges facing next-generation, wireless networks lay in efficient resource allocation and mobility management strategies that can accommodate a large number of high-data-rate users. Hierarchical or multi-tier network architectures (e.g., two-tier micro-cell/macro-cell architectures) have recently been proposed for these applications.
Assignment strategies for such hierarchical networks have heretofore been tailored towards voice users and circuit-switched services, with the objective of reducing the probability of service blocking or call dropping. These assignment strategies have focused on the velocities of mobile users relative to the center of a micro-cell or macro-cell, and micro-cell and macro-cell traversal times relative to handoff and switching times. Such assignment strategies are appropriate for voice users, who have fixed throughput rates and bounded data-delay requirements, and whose call arrival and call length processes conform to particular statistical models.
However, data users, while in some cases requiring more aggregate bandwidth than voice users, are generally more flexible with respect to delay and minimum continuous data rate requirements, and their usage patterns exhibit different statistical distributions than voice users. Assignment strategies that are appropriate for voice users may be inefficient and/or inadequate for next generation wireless networks that support both voice and data users.